CN115803205B

CN115803205B - Quality asymmetric tires

Info

Publication number: CN115803205B
Application number: CN202080102667.6A
Authority: CN
Inventors: 福田宪司; J·巴博
Original assignee: Compagnie Generale des Etablissements Michelin SCA
Current assignee: Compagnie Generale des Etablissements Michelin SCA
Priority date: 2020-06-30
Filing date: 2020-06-30
Publication date: 2025-04-29
Anticipated expiration: 2040-06-30
Also published as: US12077020B2; KR102723199B1; CN115803205A; EP4171969A1; JP7604526B2; KR20230027088A; JP2023534399A; EP4171969B1; WO2022003804A1; US20230278368A1

Abstract

The present invention provides a tire, which includes a tire top surrounded by side parts terminating in a bead configured to cooperate with a mounting rim, and includes at least one carcass reinforcement, wherein the at least one carcass reinforcement is covered from the top by a tire top reinforcement composed of multiple reinforcing cord layers, when the tire is mounted on its standard mounting rim and inflated with its nominal pressure, each side part has three points, namely an upper side point, a bottom side point, and an intermediate side point, and has an upper side part defined as being located on the outside of the radially outermost carcass reinforcement and bounded by a virtual line passing through the upper side point and a virtual line passing through the intermediate side point, and a bottom side part defined as being located on the outside of the radially outermost carcass reinforcement and bounded by a virtual line passing through the bottom side point and a virtual line passing through the intermediate side point, and the weight of the bottom side part on one side part is at least 15% lighter than the weight of the bottom side part on the other side part.

Description

Tire with asymmetric mass

Technical Field

The present invention relates to tires, and in particular to a tire having asymmetric mass from side to side.

Background

In recent years, from the viewpoints of comfort of passengers and environment, particularly, from the viewpoint of electrification toward a vehicle, improvement in quality (high-end) and quality of the vehicle have led to a desire for reduction of various noises.

It is known that noise from a tire includes various components (components), i.e., a component from external noise and a component from internal noise. The internal noise includes vibration due to excitation of the tread portion during rolling, which is transmitted to the rim, axle, suspension, and body of the vehicle, and then heard as noise inside the vehicle.

In order to improve such noise, it is known that a change in the vibration characteristics of the tire is effective. Various solutions have been proposed to improve this noise.

JPH05193310 discloses a pneumatic tire having a ratio of damping coefficients (Ho/Hi) calculated from an average thickness Go and a loss tangent tan δo (go×tan δo) of an outer side wall, and Hi calculated from an average thickness Gi and a loss tangent tan δi (gi×tan δi) of an inner side wall, the ratio being set in a range of 1.2 to 6.5 to improve comfort without deteriorating handling performance.

JPH05193311 discloses a pneumatic tire having an average thickness GU of a region of each sidewall extending from a position corresponding to the widest portion of the tire toward a tread and an average thickness GL of a region of the sidewall extending from the same position toward a bead, the two average thicknesses being set to be different from each other, the average thickness GU of a tread side region being set to be not less than 2.5mm, the average thickness GL of a bead side region being set to be less than 2.5mm and not less than 1.0mm, to reduce the tire quality without deteriorating the cut resistance of the sidewall. FR2978083 discloses a tire having maximum axial width SW and axial width RW at the beads, comprising a crown reinforcement and a radial carcass reinforcement having width TW, in which tire when the tire is mounted on its mounting rim and inflated to its in-use (operating) pressure and equilibrium conditions, the conditions Thy/sw=75%, TWIRW =85% and X/sh=50%, where X is the radial height of the tire at the maximum axial width and SH represents the radial height of the tire, Y/sh=80%, where Y is the radial height of the carcass reinforcement at the end of the crown reinforcement, and Z/sh=90%, where Z represents the radial height of the carcass reinforcement, and where the absolute value of the angle a between the tangential line and the axial direction at the point of the carcass reinforcement at the same axial position as the axial end of the crown reinforcement is less than or equal to 22 °. DE102005044354 discloses a vehicle tyre comprising a running strip, a carcass, (rigid) stiffening elements, stabilizing elements and beads. The running strip and carcass form a male shoulder that extends into the female sidewall section. The stiffening element and the stabilizing element are embedded in the bead section. JP2004359042 discloses a pneumatic tire for an automobile, which is equipped with an annular expansion section having an inner circumferential side surface facing the outer circumferential side curved surface of a rim flange on at least one side wall section, and with at least one row of projections provided continuously in the circumferential direction on the tire inner circumferential side of the expansion section. The height R1 of the peak P1 of the expansion section with the nominal diameter NR as a reference value is 55mm or more, and the height H1 of the extension line from the peak P1 of the side wall 2 is 3mm or more. The relation between the height R2 at the position P2 with the nominal diameter NR as a reference value and the height HR of the upper end face of the rim flange 21 satisfies 4mm < R2-HR <10mm. JP2013018345 discloses a tire-wheel assembly for an in-wheel motor, comprising a pneumatic tire and a wheel. The carcass is stretched onto the bead cores at both ends by the tread portions, and both ends of the carcass are folded back at the bead cores so as to hold the bead cores and the bead filler therebetween. The inner diameter of the bead section at the vehicle-mounted inner side is formed larger than the inner diameter of the bead section at the vehicle-mounted outer side to form tires having different diameters. When the tire cross-sectional height of the vehicle-mounted inside is defined as Hin, the tire cross-sectional height of the vehicle-mounted outside is defined as Hout, the height of the bead filler of the vehicle-mounted inside is defined as Fin, the height of the bead filler of the vehicle-mounted outside is defined as Fout, and K is a coefficient, k.hout/hin=fout/Fin, where 1.0.ltoreq.k.ltoreq.4.0 is satisfied (expression 1). JPH04201604 discloses a tire having different sidewall heights on the inner side and the outer side, an automobile travels with the tire being thin while traveling straight, and the contact width of the road surface with the tire is widened by pressing the tire on the outer side while cornering, so that the grip is increased. further, the inside diameter a of the tire-mounted wheel is made large, while the outside diameter B is made small. Therefore, it is possible to improve the grip without flattening the tire and the wheel and improve the running feeling at low fuel cost.

CITATION LIST

Patent literature

PTL1:JPH05193310

PTL2:JPH05193311

PTL3:FR2978083

PTL4:DE102005044354

PTL5:JP2004359042

PTL6:JP2013018345

PTL7:JPH04201604

However, with the solutions disclosed in these documents, the improvement of noise performance is not satisfactory. Also, at the same time, the deterioration of the drivability is at an unacceptable level. Therefore, it is desirable to further improve noise performance while maintaining a reasonable level of drivability.

Accordingly, there is a need for a tire that provides improved noise performance while maintaining a reasonable level of handling performance.

Definition:

"radial direction/orientation" is a direction/orientation perpendicular to the axis of rotation of the tire. This direction/orientation corresponds to the thickness orientation of the tread.

"Axial direction/orientation" is a direction/orientation parallel to the axis of rotation of the tire.

"Circumferential direction/orientation" is a direction/orientation tangential to an arbitrary circle centered on the axis of rotation. The direction/orientation is perpendicular to both the axial direction/orientation and the radial direction/orientation.

"Tire" means an elastic tire of all types, whether or not it is subjected to internal pressure.

"Ply" or "reinforcement ply" refers to a layer of material composed of a plurality of individual and/or stranded wires of metal or fiber filaments, such as steel, polyester or nylon, disposed in parallel, covered with a rubber composition. The direction of extension of such metal or fiber filaments may be different from the direction of rotation of the tire.

It is therefore an object of the present invention to provide a tire that provides an improvement in noise performance while maintaining a reasonable level of handling performance.

Disclosure of Invention

The present invention provides a tire intended for mounting on a mounting rim, said tire comprising a summit surrounded on both sides by side portions ending in beads, said beads being arranged to cooperate with said mounting rim, said tire comprising at least one carcass reinforcement extending in said summit and said side portions and anchored in said beads at both ends thereof, said at least one carcass reinforcement being covered on the radially outer side from the top by a summit reinforcement consisting of a plurality of reinforcement plies, said summit reinforcement being covered on the radially outer side from the top by a tread intended for contact with the ground during rolling, each side portion having three points, when said tire is mounted on its standard mounting rim and inflated at its nominal pressure, an upper side point defined as a point on the radially outermost carcass reinforcement at which a virtual line perpendicular to said carcass reinforcement extends from a point on the contour line of said tire intersecting an axially extreme point of the widest reinforcement ply, a bottom side point defined as a point on the contour line of said carcass reinforcement extending from the radially outermost side at a point on said radially outermost side, said virtual line extending from said point on the contour line of said carcass reinforcement at a point along the radially outer side at a point defined as a point on the bead extending from said base side at a point on the radially outermost side of said carcass reinforcement flange, said virtual line extending from said point along the length at a point on the bead which said virtual line intersects said virtual line along the bead at a point on the radially outermost side at said point along the bead at the point of said point, which is defined as the portion of the side portion outside the radially outermost carcass reinforcement defined by a virtual line passing through the upper side point and a virtual line passing through the intermediate side point, and a bottom side portion, which is defined as the portion of the side portion outside the radially outermost carcass reinforcement defined by a virtual line passing through the bottom side point and a virtual line passing through the intermediate side point, the weight of the bottom side portion on one side portion being at least 15% lighter than the weight of the bottom side portion on the other side portion, the tire having a predetermined mounting side (inside-outside), and the lighter bottom side portion being located inside the predetermined mounting side, the upper side portion of the non-lighter bottom side portion being lighter than the weight of the upper side portion provided with the lighter bottom side portion.

This configuration (arrangement) provides an improvement in noise performance while maintaining a reasonable level of drivability.

Since the weight of the bottom side portion on one side portion is at least 15% lighter than the weight of the bottom side portion on the other side portion, the dynamic torsional rigidity (rigidity) of the tire, that is, a component of the dynamic rigidity of the tire that transmits vibrations from the ground, can be effectively reduced. Thus, noise performance can be improved.

If the weight difference between the two bottom side portions is less than 15%, there is a risk that the improvement of noise performance will be insufficient due to insufficient dynamic torsional rigidity reduction. By setting the weight difference between the two bottom side portions to at least 15%, noise performance can be improved.

The weight of the bottom side portion on one side portion is preferably at least 20% lighter than the weight of the bottom side portion on the other side portion.

Since the bottom side portion is defined as the portion of the side portion that is located outside the radially outermost carcass reinforcement between a bottom side point, which is defined as a point on the radially outermost carcass reinforcement at which a virtual line perpendicular to the carcass reinforcement extends from a point on the contour line of the tire that intersects a radially outermost virtual horizontal line touching the rim flange, and an intermediate side point, which is defined as a point on the radially outermost carcass reinforcement at which a length along the carcass reinforcement from the bottom side point is 60% along the length of the carcass reinforcement between the upper side point and the bottom side point, the side portion can maintain a sufficient material volume in order to perform a reasonable level of handling performance. Thus, the noise performance can be improved while maintaining a reasonable level of drivability.

If the intermediate side point is located at a position along the length of the carcass reinforcement from the bottom side point that exceeds 60% of the length of the carcass reinforcement between the upper side point and the bottom side point, there is a risk that the side portions as a whole cannot maintain a sufficient material volume to perform a reasonable level of handling properties. By setting this intermediate side point at a position along the length of the carcass reinforcement from the bottom side point of 60% of the length of the carcass reinforcement between the upper side point and the bottom side point, it is possible to improve noise performance while maintaining a reasonable level of handling performance.

Since the tire has a predetermined mounting side (inside-outside), and the lighter bottom side portion is located inside the predetermined mounting side, it is possible to improve noise performance while maintaining a reasonable level of drivability with high efficiency, because the rigidity of the bottom side portion is more important on the outside than on the inside.

Since the upper side portion without the lighter bottom side portion is lighter in weight than the upper side portion provided with the lighter bottom side portion, the noise performance can be further improved because the lighter upper side portion without the lighter bottom side portion contributes to the dynamic torsional rigidity reduction.

In another preferred embodiment, the weight of the bottom side portion on one side portion is at most 50% lighter than the weight of the bottom side portion on the other side portion.

If the weight of the bottom side portion on one side portion is 50% or more (i.e., more than 50%) lighter than the weight of the bottom side portion on the other side portion, there is a risk of deterioration in drivability or durability due to insufficient rubber volume at the bottom side portion. By setting the weight of the bottom side portion on one side portion to be at most 50% lighter than the weight of the bottom side portion on the other side portion, noise performance can be improved while maintaining a reasonable level of durability performance and drivability.

The weight of the bottom side portion on one side portion is preferably at most 45% lighter than the weight of the bottom side portion on the other side portion, more preferably at most 40% lighter than the weight of the bottom side portion on the other side portion.

In another preferred embodiment, the contour line of the tire between the two side portions is asymmetrical.

According to this configuration, such a tire can be manufactured with lower consumption of raw materials, whereby the cost effectiveness of the tire can be improved.

In another preferred embodiment, the contour line of the tire between the two side portions is symmetrical.

According to this configuration, such a tire can be manufactured using an existing mold having a standard profile on the side portion, whereby the cost effectiveness of the tire can be improved.

Advantageous effects of the invention

According to the configuration described above, improvement of noise performance can be provided while maintaining a reasonable level of drivability.

Drawings

Other features and advantages of the invention derive from the following description, with reference to the accompanying drawings, which show, by way of non-limiting example, embodiments of the invention.

In these figures:

FIG. 1 is a schematic cross-sectional view of a tire according to a first embodiment of the present invention;

FIG. 2 is an enlarged schematic view of the portion indicated as II in FIG. 1;

FIG. 3 is a schematic cross-sectional view of a tire according to a second embodiment of the invention;

fig. 4 is an enlarged schematic view of a portion indicated as IV in fig. 3.

Detailed Description

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

A tire 1 according to a first embodiment of the present invention will be described with reference to fig. 1 and 2. Fig. 1 is a schematic cross-sectional view of a tire according to a first embodiment of the present invention. Fig. 2 is an enlarged schematic view of the portion indicated as II in fig. 1.

The tyre 1 is a tyre having dimensions 235/45R18 intended for mounting on a mounting rim W and comprising a summit (summit) 2, said summit 2 being surrounded on both sides by side portions 3, said side portions 3 ending in beads 4 arranged to cooperate with the mounting rim W. The tyre 1 comprises at least one carcass reinforcement 5, said at least one carcass reinforcement 5 extending in the summit 2 and in the side portions 3 and being anchored in the beads 4 at both ends thereof. The mounting rim W is terminated on both axial sides by rim flanges RF. In this first embodiment, the tyre 1 has one carcass reinforcement 5.

As shown in fig. 1, said at least one carcass reinforcement 5 is covered from the top radially outside by a summit reinforcement 6 consisting of a plurality of reinforcing plies 61 and the summit reinforcement 6 is covered from the top radially outside by a tread 7 intended for contact with the ground during rolling. In this first embodiment, the summit reinforcement 6 is composed of two reinforcement plies 61.

As shown in fig. 1 and 2, when the tyre 1 is mounted on its standard mounting rim and inflated at its nominal pressure, each side portion 3 has three points, namely an upper point 33 defined as the point on the radially outermost carcass reinforcement 5 at which a virtual line VU1 perpendicular to said carcass reinforcement 5 starts from the point on the contour of the tyre 1 intersecting the virtual horizontal line VU2 extending from the axial end point of the widest reinforcement ply 61, a bottom point 35 defined as the point on the radially outermost carcass reinforcement 5 at which a virtual line VB1 perpendicular to said carcass reinforcement 5 starts from the point on the contour of the tyre 1 intersecting the virtual horizontal line VB2 touching the radially outermost part of the rim flange RF, and a middle point 34 defined as the point on the radially outermost carcass reinforcement 5 at which the length of said carcass reinforcement 5 from the bottom point 35 starts along the length of said carcass reinforcement 5 between the bottom point 33% of the bottom point 35. According to the ETRTO standard manual 2020, the standard mounting rim size is 8.0 inches and the nominal pressure is 290kPa with extra load and 250kPa without extra load.

As shown in fig. 1 and 2, each side portion 3 comprises an upper side portion 31 defined as the portion of the side portion 3 outside the radially outermost carcass reinforcement 5 delimited by a virtual line passing through an upper side point 33 and a virtual line passing through an intermediate side point 34, and a bottom side portion 32 defined as the portion of the side portion 3 outside the radially outermost carcass reinforcement 5 delimited by a virtual line passing through a bottom side point 35 and a virtual line passing through an intermediate side point 34. The weight of the bottom side portion 32 on one side portion 3 is at least 15% lighter than the weight of the bottom side portion 32 on the other side portion 3.

As shown in fig. 1 and 2, the profile of the tyre 1 between the two side portions 3 is asymmetrical, so that the weight of the bottom side portion 32 on one side portion 3 is at least 15% lighter than the weight of the bottom side portion 32 on the other side portion 3. The contour line of the side portion 3 provided with the lighter (lighter) bottom side portion 32 is recessed (concave) from (relative to) the contour of the side portion 3 not provided with the lighter bottom side portion 32. The weight of the bottom side portion 32 on one side portion 3 is at most 50% lighter than the weight of the bottom side portion 32 on the other side portion 3. Further, the upper side portion 31 without the lighter bottom side portion 32 is lighter in weight than the upper side portion 32 provided with the lighter bottom side portion 32.

When comparing the weight of the bottom side portion 32 and/or the weight of the upper side portion 31, the upper side portion 31 should be defined by a virtual line passing through the upper side point 33, a virtual line passing through the intermediate point 34 and the outermost carcass reinforcement 5, and the bottom side portion 32 should be defined by a virtual line passing through the bottom side point 35, a virtual line passing through the intermediate point 34 and the outermost carcass reinforcement 5. The virtual lines passing through the upper side point 33, the middle side point 34 and the bottom side point 35 should be respectively identical from one side portion 3 to the other side portion 3, for example virtual line VU1 as the virtual line passing through the upper side point 33, virtual line VM perpendicular to the carcass reinforcement 5 as the virtual line passing through the middle side point 34, and virtual line VB1 as the virtual line passing through the bottom side point 35.

The comparison of the weight of the bottom side portion 32 and/or the weight of the upper side portion 31 should be made by comparing the overall weight of the bottom side portion 32 and/or the upper side portion 31. If the weight of the bottom side portion 32 and/or the weight of the upper side portion 31 can be considered uniform in circumferential orientation, a comparison of these weights can be made by comparing the weights of a portion extracted along the axial section.

As shown in fig. 1 and 2, the tire 1 has a predetermined mounting side (inside-outside), wherein in the case of this example, the outside is left side and the inside is right side in the drawing, and the lighter bottom side portion 32 is located inside the predetermined mounting side. The predetermined mounting side is generally a case (example) in which it is indicated on the surface of the side face portion (side wall) by a character such as "OUTSIDE (outside)", "INSIDE (INSIDE)", or the like indicator (not shown).

Since the weight of the bottom side portion 32 on one side portion 3 is at least 15% lighter than the weight of the bottom side portion 32 on the other side portion 3, the dynamic torsional rigidity of the tire 1, that is, one component of the dynamic rigidity of the tire that transmits vibrations from the ground can be effectively reduced. Thus, noise performance can be improved.

If the weight difference between the two bottom side portions 32 is less than 15%, there is a risk that the improvement of noise performance will be insufficient due to the insufficient reduction of dynamic torsional rigidity. By setting the weight difference between the two bottom side portions 32 to at least 15%, noise performance can be improved.

The weight of the bottom side portion 32 on one side portion 3 is preferably at least 20% lighter than the weight of the bottom side portion 32 on the other side portion 3.

Thanks to the bottom side portion 32, wherein the bottom side portion 32 is defined as the portion of the side portion 3 that is located outside the radially outermost carcass reinforcement 5 between a bottom side point 35 and an intermediate side point 34, the bottom side point 5 is defined as a point on the radially outermost carcass reinforcement 5 at which a virtual line perpendicular to the carcass reinforcement 5 extends from a point on the contour line of the tire 1 that intersects a radially outermost virtual horizontal line touching the rim flange RF, the intermediate side point 34 is defined as a point on the radially outermost carcass reinforcement 5 at which the length along the carcass reinforcement 5 from the bottom side point 35 is 60% along the length of the carcass reinforcement 5 between the upper side point 33 and the bottom side point 35, whereby the side portion 3 can maintain a sufficient material volume for performing a reasonable level of handling performance. Thus, the noise performance can be improved while maintaining a reasonable level of drivability.

If the intermediate side point 34 is located at a position along the carcass reinforcement 5 that is more than 60% of the length along the carcass reinforcement 5 between the upper side point 33 and the bottom side point 35, there is a risk that the side portions 3 as a whole cannot maintain a sufficient material volume to perform a reasonable level of handling properties. By setting this intermediate side point 34 at a position along the carcass reinforcement 5 at 60% of the length between the upper side point 33 and the bottom side point 35, the noise performance can be improved while maintaining a reasonable level of handling performance.

Since the weight of the bottom side portion 32 on one side portion is at most 50% lighter than the weight of the bottom side portion 32 on the other side portion, noise performance can be improved while maintaining a reasonable level of durability performance and drivability.

If the weight of the bottom side portion 32 on one side portion is 50% or more (i.e., more than 50%) lighter than the weight of the bottom side portion 32 on the other side portion, there is a risk of deterioration in drivability or durability due to insufficient rubber volume at the bottom side portion 32.

The weight of the bottom side portion 32 on one side portion 3 is preferably at most 45% lighter than the weight of the bottom side portion 32 on the other side portion 3, more preferably at most 40% lighter than the weight of the bottom side portion 32 on the other side portion 3.

Since the upper side portion 31 without the lighter bottom side portion 32 is lighter in weight than the upper side portion 31 provided with the lighter bottom side portion 32, the noise performance can be further improved because the lighter upper side portion 31 without the lighter bottom side portion 32 contributes to the dynamic torsional rigidity reduction.

Since the tire 1 has a predetermined mounting side (inside-outside), and the lighter bottom side portion 32 is located inside the predetermined mounting side, it is possible to improve noise performance while maintaining a reasonable level of drivability with high efficiency, because the rigidity of the bottom side portion 32 is more important on the outside than on the inside.

Since the contour line of the tire 1 between the two side portions 3 is asymmetrical, such a tire can be manufactured with a lower consumption of raw materials, whereby the cost effectiveness of the tire 1 can be improved.

In the case of mounting the tire 1 onto the mounting rim W, it is preferable to use a mounting rim with an inner adjustment in which the attachment disc portion of the mounting rim W is axially offset outward from the axial center of the mounting rim W, instead of using a mounting rim with a zero adjustment (the attachment disc portion of the mounting rim W is on the same plane as the axial center of the mounting rim W) or an outer adjustment (the attachment disc portion of the mounting rim W is axially offset inward from the axial center of the mounting rim W) to obtain effective noise performance improvement.

In the case of providing a plurality of carcass reinforcements 5, the upper, intermediate and lower points 33, 34, 35 should be considered to be located on the radially outermost carcass reinforcement 5, excluding the turned-around portions of the carcass reinforcements 5 around the beads 4.

A similar effect can be obtained by adding weight to one side of the bottom side portion 32 (i.e., the bottom side portion 32 of one side) rather than reducing the weight of one side of the bottom side portion 32, but it is preferable to reduce the weight of one side of the bottom side portion 32 in view of energy and raw material consumption.

In order to maintain reasonable durability, it may be preferable for the lightened bottom-side portion 32 outside the carcass reinforcement 5 to maintain a minimum thickness at least equal to 1.0 mm.

A tire 21 according to a second embodiment of the present invention will be described with reference to fig. 3 and 4. Fig. 3 is a schematic cross-sectional view of a tire according to a second embodiment of the invention. Fig. 4 is an enlarged schematic view of the portion indicated IV in fig. 3. The structure of the second embodiment is similar to that of the first embodiment except for the configuration shown in fig. 3 and 4, and thus will be described with reference to fig. 3 and 4.

As shown in fig. 3 and 4, the tyre 21 is intended for mounting on a mounting rim W and comprises a summit 22 surrounded on both sides by side portions 23, said side portions 23 ending in beads 24, said beads 24 being arranged to cooperate with the mounting rim W. The tyre 21 comprises at least one carcass reinforcement 25, said at least one carcass reinforcement 25 extending in the summit 22 and in the side portions 23 and being anchored in the beads 24 at both ends thereof. The mounting rim W is terminated on both axial sides by rim flanges RF. In this second embodiment, the tyre 21 has one carcass reinforcement 25.

As shown in fig. 3, said at least one carcass reinforcement 25 is covered from the top radially outside by a summit reinforcement 26 consisting of a plurality of reinforcement plies 261 and said summit reinforcement 26 is covered from the top radially outside by a tread 27, said tread 27 being intended to be in contact with the ground during rolling. In this second embodiment, the summit reinforcement 26 is composed of two reinforcement plies 261.

As shown in fig. 3 and 4, when the tire 21 is mounted on its standard mounting rim and inflated at its nominal pressure, each side portion 23 has three points, namely, an upper side point 233, which is defined as a point on the radially outermost carcass reinforcement 25 at which a virtual line VU1 perpendicular to the carcass reinforcement 25 extends from a point on the contour of the tire 21 intersecting a virtual horizontal line VU2 extending from the axial end point of the widest reinforcement ply 261, a bottom side point 235, which is defined as a point on the radially outermost carcass reinforcement 25 at which a virtual line VB1 perpendicular to the carcass reinforcement 25 extends from a point on the contour of the tire 21 intersecting a virtual horizontal line VB2 touching the radially outermost rim flange RF, and a middle side point 234, which is defined as a point on the radially outermost carcass reinforcement 25 at which a length along the carcass reinforcement 25 from the bottom side point 235 is 60% along the length between the bottom side point 233 and the upper side point 235. According to the ETRTO standard manual 2020, the standard mounting rim size is 8.0 inches and the nominal pressure is 290kPa with extra load and 250kPa without extra load.

As shown in fig. 3 and 4, each side portion 23 comprises an upper side portion 231 defined as the portion of the side portion 23 outside the radially outermost carcass reinforcement 25 defined by the virtual line passing through the upper side point 233 and the virtual line passing through the intermediate side point 234, and a bottom side portion 232 defined as the portion of the side portion 23 outside the radially outermost carcass reinforcement 25 defined by the virtual line passing through the bottom side point 235 and the virtual line passing through the intermediate side point 234. By means of the lightweight (lightweight) bottom side portion 2321, the weight of the bottom side portion 232 on one side portion 23 is at least 15% lighter than the weight of the bottom side portion 232 on the other side portion 23, and the contour of the tire 21 between the two side portions 23 is symmetrical.

Since the contour line of the tire 21 between the two side portions 23 is symmetrical, such a tire 21 can be manufactured using an existing mold having a standard contour on the side portions 23, whereby the cost effectiveness of the tire 21 can be improved.

The lightweight bottom side portion 2321 may be made of foam rubber, a material having a low specific gravity such as plastic or resin, a material having a low density, or a mixture of these materials.

A similar effect may be achieved by adding weight to one side of the bottom side portion 232 (i.e., the bottom side portion 232 of one side) at least partially instead of using the light weight bottom side portion 2321, but in view of energy and raw material consumption, it is preferable to reduce the weight of one side of the bottom side portion 232 by means of the light weight bottom side portion 2321.

The invention is not limited to the examples described and presented and various modifications may be made without departing from its framework.

Example

To confirm the effects of the present invention, two types of examples and other types of reference examples to which the present invention was applied were prepared.

Example 1 is a tire as described in the above first embodiment, which is provided so that one side of the bottom side portion (i.e., the bottom side portion of one side) is 25.4% lighter than the other side of the bottom side portion (i.e., the bottom side portion of the other side), considering the area defined by the virtual line VM and the virtual line VB 1. Example 2 is a tire similar to example 1, considering an area equivalent to that of example 1, which is provided so that one side of the bottom side portion is 32.3% lighter than the other side of the bottom side portion. The reference example is to provide tires of equal weight on both bottom side portions. Considering the area defined by the virtual line VU1 and the virtual line VM, the weight of the upper side portion of each of the example and the reference example is equal between the two side portions. All examples and reference examples employed the same tire size 235/45R18 and had the same internal construction using the same materials as a standard radial pneumatic tire.

Noise performance test:

unused test tires were mounted on all four wheels of a2,500 cc rear wheel drive hybrid vehicle. On straight weather-resistant asphalt, the vehicle decelerates (coasts) from 105kph to 50kph with the engine off. In-vehicle noise is measured using a microphone positioned near the window at the occupant's ear. An average a-weighted sound pressure level between 50 and 500Hz from 85kph to 75kph is calculated.

The results are shown in table 1. In this table 1, the results are presented by dB (a) differences relative to the reference example, lower values indicating better performance.

Handling property test:

the cornering power of an unused test tire mounted on a standard rim and inflated to a nominal internal pressure was measured using a flat belt tire tester. When the tire was driven at a constant speed of 80kph, a load of 460kg was applied, the lateral force at a slip angle of ±1° was measured, and the lateral forces measured at +1° and-1 ° were averaged.

The results are also shown in table 1. In this table 1, the results are presented with an index of 100 for the reference example, with higher numbers indicating better performance.

TABLE 1

	Example 1	Example 2	Reference example
				Noise performance (dB (A))	-0.9	-1.5	-
Handling properties (index)	100	100	100

As can be seen from table 1, the examples show improved noise performance while maintaining drivability.

List of reference numerals

1. 21 Tyre

2. 22 Tyre top

3. 23 Side portions

31. 231 Upper side portion

32. 232 Bottom side portion

33. 233 Upper side point

34. 234 Medial side point

35. 235 Bottom side point

2321. Lightweight bottom side portion

4. 24 Bead

5. 25 Carcass reinforcement

6. 26 Summit reinforcement

61. 261 Reinforcing ply

7. 27 Tread surface

Claims

1. A tyre (1) intended to be mounted on a mounting rim (W), the tyre (1) comprising a tread (2) surrounded on both sides by side portions (3) terminating in beads (4), the beads (4) being arranged to cooperate with the mounting rim (W), the tyre (1) comprising at least one carcass reinforcement (5) extending in the tread (2) and in the side portions (3) and anchored at both ends in the beads (4), the at least one carcass reinforcement (5) being covered radially on the outside from the top by a tread reinforcement (6) consisting of a plurality of reinforcing plies (61), the tread reinforcement (6) being covered radially on the outside from the top by a tread (7) intended to come into contact with the ground during rolling,

When the tire (1) is mounted on its standard mounting rim and inflated to its nominal pressure, each side portion (3) has three points:

an upper point (33) defined as a point on the radially outermost carcass reinforcement (5) at which an imaginary line perpendicular to said carcass reinforcement (5) extends from the point on the contour of said tire (1) where it intersects an imaginary horizontal line extending from the axial end point of the widest reinforcing ply (61);

a bottom point (35) defined as a point on the radially outermost carcass reinforcement (5) at which an imaginary line perpendicular to said carcass reinforcement (5) extends from the point on the contour of said tyre (1) intersecting a radially outermost imaginary horizontal line touching the rim flange (RF);

an intermediate side point (34) defined as a point on the radially outermost carcass reinforcement (5) at which the length along the carcass reinforcement (5) from the bottom side point (35) is 60% of the length along the carcass reinforcement (5) between the upper side point (33) and the bottom side point (35),

Each side portion (3) comprises:

an upper lateral portion (31) defined as the portion of the lateral portion (3) situated outside the radially outermost carcass reinforcement (5) delimited by an imaginary line passing through the upper lateral point (33) and an imaginary line passing through the intermediate lateral point (34);

a bottom side portion (32) defined as the portion of the side portion (3) situated outside the radially outermost carcass reinforcement (5) delimited by an imaginary line passing through the bottom side point (35) and an imaginary line passing through the intermediate side point (34),

The weight of the bottom side portion (32) on one side portion (3) is at least 15% lighter than the weight of the bottom side portion (32) on the other side portion (3),

The tire is characterized in that the tire (1) has a predetermined installation side, and wherein the lighter bottom side portion (32) is located inside the predetermined installation side, and wherein the weight of the upper side portion (31) without the lighter bottom side portion (32) is lighter than the weight of the upper side portion (31) provided with the lighter bottom side portion (32).

2. The tire (1) according to claim 1, wherein the weight of the bottom side portion (32) on one side portion (3) is at most 50% lighter than the weight of the bottom side portion (32) on the other side portion (3).

3. Tyre (1) according to claim 1 or claim 2, wherein the profile of the tyre (1) is asymmetrical between the two side portions (3).

4. Tyre (1) according to claim 1 or claim 2, wherein the profile of the tyre (1) is symmetrical between the two side portions (3).